1) Weigh foods you eat regularly and see if you were accurate with your guesses (if you don‘t weigh things on a daily basis).
2) Report your worst days rather than your best days. There is little point reporting 1,500 calories on a daily basis if this is your absolute lowest intake and you are only eating this much two days out of the week.
3) Make sure to give yourself leeway if you eat out a lot. If you have dinner at a restaurant it is unlikely you will know how many calories you eat.